Basic tissues Epithelium Connective tissues Muscles Nervous tissue
Basic tissues • • Epithelium Connective tissues Muscles Nervous tissue Jeanne Adiwinata Pawitan Dept. of Histology FMUI
Basic tissues • Epithelium: cells, intercellular substance/extracellular matrix – basement membrane • *Connective tissue: intercellular substance↑ • Muscle: muscle cells* = muscle fibers • Nerve*: ° Neurons ° Neuroglial cells (support, protect neurons)
Epithelium
Epithelium (and glands) • Layers ° Single • Simple • (Pseudostratified) ° Multiple • Stratified • (Transitional) • Shape ° Squamous ° Cuboidal ° Columnar (torax) • Location
Polarity and cell surface specializations • Morphological domain • Biochemical domain Polarity • Functional domain v. Apical domain – free surface – lumen v. Basolateral domain v. Basal - basal lamina v. Lateral – other cells
Apical domain - lumen • Microvilli • Cilia ° Kinocilia ° Stereocilia • Ion channels • Aquaporins • • Carrier proteins H+- ATPase Glycoproteins Hydrolytic enzymes
Basolateral domain • Intercellular interdigitation, basal enfoldings • Junctional specialization • Receptors ° Hormones ° Neurotransmitters • Na+-K+ ATPase • Ion channels • Sites for constitutive secretions
Junctional specialization • Lateral membrane specialization – terminal bars (LM) – junctional complexes (EM) ° Occluding junction, tight junction, zonula occludens ° Adhering junction • Zonula adherens -zonulae adherentes • Fascia adherens • Macula adherens (desmosome) - hemidesmosome ° Gap junction
Connective tissue
Connective tissues • Mesenchyme (embryo) – mucosa /gelatinosa • Connective tissue proper ° ° Loose (areolar) connective tissue Reticular connective tissue Adipose tissue Dense connective tissue areolar CT • Dense regular connective tissue Ø Dense regular collagenous connective tissue Ø Dense regular elastic connective tissue • Dense irregular connective tissue • Specialized connective tissue (cartilage, bone, blood)
Cells of connective tissue • • Mesenchymal cells - mesenchyme Fibroblasts/fibrocytes Histiocytes/macrophages Mast cells Pericytes Adipose cells Reticular cells – reticular CT Transient cells: plasma cells, leucocytes, macrophages
Intercellular substance/ extracellular matrix • Ground/amorphous substance (gel like)– tissue fluid ° Glycosaminoglycans (GAG) (hyaluronic acid, heparin, sulfated GAG) ° Proteoglycans ( certain GAG – Protein) ° Adhesive glycoproteins (fibronectin, laminin, entactin, tenascin, chondronectin, osteonectin) • Fibers ° Collagen type I – VII • Reticular (type III collagen) ° Elastic fibers
Basement membrane • Basal lamina ° Lamina lucida • laminin, entactin • Transmembrane protein: integrin, dystroglycan ° Lamina densa (perlacan-type IV collagen meshwork-perlacan, fibronectin) • Lamina reticularis: type I, III collagen
Muscles
Muscles • Striated muscle – characteristic striation – specific arrangement of myofilament (contractile protein in a myofibril: myosin, actin) v parallel arrays v interdigitating ° skeletal muscle ° cardiac muscle regularly repeated arrangement in myofibril • Smooth muscle v Myoepithelial cells –glandular unit in glands v Myofibroblast – wound contraction, tooth eruption
Unique terms in muscle • Sarcolemma = cell membrane • Sarcoplasm = cytoplasm • Sarcoplasmic reticulum = smooth surfaced endoplasmic reticulum (SER) • Sarcosome = mitochondria • muscle fiber = muscle cell
Smooth muscle • Location: wall of hollow organ - lumen ° ° ° Digestive system Reproductive system Urinary system Respiratory system Ducts - large (glands) Dermis (skin) • Function: ° contraction ° Protein synthesis extra cell: collagen, elastin, glycosaminoglycans, proteoglycans, growth factors
Smooth muscle • contraction - involuntary – controlled by ° Autonomic nervous system (sympathetics, parasympathetics) ° Hormone: bradykinin ° Local physiological condition • Every fiber – lined by external lamina (outside sarcolemma) ° reticular fiber - embedded in external lamina – surrounding each muscle cell – function: control and unify the strength of muscle fiber contraction
Smooth muscle fiber • Shape : fusiform, elongated –Ø 5 -6 μm, length 0. 2 mm • Surrounded by sarcolemma (cell membrane) • Nucleus - center – oval – 1 -2 nucleolei – at contraction nucleus bottle opener • HE: cytoplasm – homogenous – acidophilic • Iron hematoxylin – in sarcoplasm: ° Dense body – attached at the inside of cell membrane ° Longitudinal lines groups of myofilaments
Smooth muscle fiber • Form sheets/layers – usually 2 layers – perpendicular • fibers –closely packed – thin part >< thick part ° Cross section – fiber diameter ≠ – section nucleus (+)/(-) • Individual cell
Innervation – smooth muscle fiber • Neuromuscular junction usually en passant type ° Bulging of axon ° Containing synaptic vesicles • Nor epinephrine – sympathetic • Acetylcholine – parasympathetic • Type ° multi unit –individual innervation (iris, vas deferens ° Intermediate (mixed 30 -60% - individual) ° Visceral – some fibers – 1 neuromuscular junction – gap junction/nexus (uterus, GI tract) – other influencing factor • Humoral factor : oxytocin • Micro environmental factor : stretching (intestines)
Cardiac muscle • Development: Myoepicardial mantle in splanchnic mesenchyme epicardium + myocardium • Cardiac muscle ° Cardiac muscle fiber–branching-anastomosing network – arranged in layers (laminae) ° Between fibers – connective tissue ° Connective tissue between laminae – contains: • Blood vessels capillaries network –in connective tissue between each fiber • Nerves • conducting system – in heart
Cardiac muscle fiber • • Striated, branching Length 15 -80 μm Nucleus 1 (occasionally 2) – center – big –oval Between cells (at the end) - intercalated disk consist of: ° Transverse portion: facia adherens ( Z disk), desmosome ° Lateral portion: gap junction (also found in regions side by side contact – long. )
Sarcoplasm contains • Myofibrils Ø-1 -2 μm –longitudinal –regularly arranged striated (longitudinal section): ° A band – (anisotropic on polarized light dark) ° I band– (isotropic on polarized light) • EM: Sarcoplasmic reticulum = SER ° ° ° Network around myofibril Function: intracellular Ca storage (< skeletal muscle) Small terminals (terminal cisternae -) The rest = longitudinal sarcotubule + branches Contraction needs active transport of Ca from extra cell • membrane contains junctional feet (= voltage gated Ca release channels)
Sarcoplasm contains • Organels ° Mitochondria >>> - ½ volume – cardiac muscle ° Myoglobin O 2 transport ° Glycogen particle energy source for contraction ( with lipid)
Cardiac muscle fiber – T tubule • EM: Sarcolemma – tubular invagination – transverse – branching - anastomosing T tubule (transverse tubule) • Intertwine among myofibril • Location: around Z line – 1/sarcomere ° Open to extra cellular compartment -lined by external lamina ° Ø 2. 5 X T tubule in skeletal muscle • Function: facilitate conduction – depol. wave -along sarcolemma • Associated with sarcoplasmic reticulum: T tubule + small terminals dyad
Myofibrils • A band (dark) – H band (light) – M line • I band (light) – Z line (Z disk, dark) • Sarcomere = myofibril region between 2 Z line = 1 contractile unit • Contraction: ° ° I band - shortened H band - disappeared A band - constant Z line - approaching each other
Cardiac muscle fiber-atrium • Ø < fiber in ventricle myoendocrine cells • Contains granules - cardiodilatin (CDD)/Atrial Natriuretic (Poly)peptide (ANP) – esp. in right atrium ° ANP – regulation of fluid –electrolyte balance • Efferent arteriole constriction diuresis, sodium excretion↑ • Sodium, water resorption in kidneys (renal tubules)↓ blood pressure ↓ • Vasodilatation • inhibit the release of arginine-vasopressin (posterior hypophysis), and aldosterone (adrenal cortex)
Skeletal muscle • investments ° Epimysium – muscle – irregular dense collagenous connective tissue ° Perimysium – fascicles (bundles) - < dense ° Endomysium – muscle fiber (cell) - reticular fiber, basal lamina / external lamina • cell ° Skeletal muscle fibers – striated – parallel ° Satellite cells
Skeletal muscle cells/fibers • Development: myoblast – parallel end –end fused myotube – formed myofibril skeletal muscle fiber • Shape: long, tubular – Ø 10 -100μm • Between fibers: endomysium + continuous capillaries – parallel to fiber • Skeletal muscle fiber – non branching -striated multinucleated • Nuclei – periphery – in a row – inside cell membrane (sarcolemma) • EM: Sarcolemma invaginate T tubule (transverse tubule)
Sarcoplasm: contains • A lot of myofibril Ø-1 -2 μm –longitudinal – along the fiber – regularly arranged striation in longitudinal section: ° A band – (anisotropic on polarized light dark) ° I band– (isotropic on polarized light) • EM: Sarcoplasmic reticulum = smooth surface endoplasmic reticulum ° Form a network around myofibril ° Function: intracellular Ca storage (esc. terminal cysterna) ° A-I junction – dilated terminal cysterna • The membrane has junctional feet (= voltage gated Ca release channels) ° The rest = longitudinal sarcotubules + their branches
T tubule • Tubular invagination –transversal – branchinganastomosing – intertwine among myofibril • Location: transversal plane - A-I junction 2 in each sarcomere • To extra cell - open • Associated with sarcoplasmic reticulum • Function: facilitate conduction of depol wave along sarcolemma • T tubule + 2 terminal cysternae triad ° function: spreading of depol wave – fast – from sarcolemma – trough out the cell – to terminal cysterna
Myofibril • A band (dark) – H band – pale –M line • I band (light) –Z line, Z disk – thin, dark • Sarcomere = myofibril area between 2 Z line = contractile unit of skeletal muscle fiber • Contraction: ° ° I band shortened H band disappeared A band remain unaltered Z line – move closer together
Satellite cells • Satellite cells = regenerative cells • Small cell – location: shallow depression – muscle cell’s surface • External lamina – shared with muscle cell → inside external lamina • Nucleus-one - > dense - > coarse
Myotendinuous junction • Connective tissue–muscle – tendon – continuous ° Cells tapered – fluted (deeply folded) ° Collagen fibers-tendon – penetrate • Infoldings • Endomysium – continuous – reticular fibers
Innervation of skeletal muscle • Motor nerve fibers (α motor neurons –axonmyelinated) branching – unmyelinated (Schwann cells +) – terminal dilated myoneural junction (motor end plate) ° Axon terminal ° Synaptic cleft ° Muscle cell membrane • Sensory nerve fibers ° muscle spindles – among muscle cells –stretch Rx ° Golgi tendon organ (neurotendinuous spindle)– inhibitory feedback - α motor neurons - relax
Regeneration - muscles • Skeletal muscle – regeneration (+) ° Skeletal muscle fiber ≠ mitosis ° Satellite cells • Injury: satellite cells - mitosis – hyperplasia • At muscle building: satellite cell – muscle fiber fusion mass increase hypertrophy • Cardiac muscle - ≠ regeneration, fibroblast – connective tissue (scar) • Smooth muscle – regeneration (+)
Regeneration – smooth muscle • Injury formation of new fibers ° Mitosis – smooth muscle fiber (GI tr. , urin. tr. ) ° Differentiation - pericyte – blood vessel • Uterus –pregnant – smooth muscle ° hyperplasia - mitosis ° hypertrophy
Nervous tissue
Neurons • Cell body (soma, perikaryon) • Dendrite (multiple) - branching • Axon (single) – long - branching ° Axon Hillock ° Axon terminals, end bulbs, terminal boutons → synapse
Specialized cells
Specialized cells • • Protein secreting cells Steroid secreting cells Neuroendocrine cells Cells in organs → other modules
Protein secreting cells • Ex. : chief cells (stomach), acinar cells (pancreas) • Shape: columnar, truncated pyramid, etc • Basal cytoplasm - basophilic ° Nucleus ° Rich in RER, polysome • Apical cytoplasm - acidophilic ° Secretory granules – proenzyme (zymogen)
Steroid secreting cells • Ex: spongiocytes (adrenal cortex) • Shape: polyhedral • Cytoplasm ° Extensive network of SER ° Lipid droplets – appear vacuolated
Neuroendocrine cells • Argentaffin, argyrophilic – silver staining • APUD= amine precursor uptake decarboxylation • DNES= diffuse neuroendocrine system • Location: epithelium/glands – systems • Secretory granules –at basal cytoplasm/ near blood vessel
Stem cells
Stem cells • Fertilization → 2 -4 cells → morula (8 cells) →blastocyst ° Trophectoderm → placenta ° Inner cell mass → embryo ↓ Embryonic stem cells → determined stem cells (connective tissue, blood) → unipotential stem cells → differentiation (precursors of certain cells) → certain cells
Stem cells • Totipotent – can give rise to cells of all orders • Pluripotent – can develop in any one of several possible ways, or affect more than one organ/tissue – multipotent • Unipotent – can give rise to cells of one order only
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